U.S. patent application number 13/495388 was filed with the patent office on 2012-12-20 for electric lawn mowers.
This patent application is currently assigned to MAKITA CORPORATION. Invention is credited to Hideki ABE, Masahiro ITO, Ryosuke ITO, Syusuke ITO.
Application Number | 20120317949 13/495388 |
Document ID | / |
Family ID | 46319550 |
Filed Date | 2012-12-20 |
United States Patent
Application |
20120317949 |
Kind Code |
A1 |
ABE; Hideki ; et
al. |
December 20, 2012 |
ELECTRIC LAWN MOWERS
Abstract
An electric lawn mower may include a switch assembly including a
first switch, a second switch and a main switch. When the main
switch is turned on an electric motor is started. The first and
second switch may include first and second actuators, respectively.
When the switch assembly is operated according to a proper
operation sequence, the first actuator and the second actuator may
interact with each other to activate the main switch, and when the
switch is operated according to an improper operation sequence, the
first actuator and the second actuator may not interact with each
other, so that the main switch is not activated.
Inventors: |
ABE; Hideki; (Anjo-shi,
JP) ; ITO; Ryosuke; (Anjo-shi, JP) ; ITO;
Masahiro; (Numazu-shi, JP) ; ITO; Syusuke;
(Anjo-shi, JP) |
Assignee: |
MAKITA CORPORATION
Aichi
JP
|
Family ID: |
46319550 |
Appl. No.: |
13/495388 |
Filed: |
June 13, 2012 |
Current U.S.
Class: |
56/10.5 ;
56/11.9 |
Current CPC
Class: |
G05G 5/005 20130101;
H01H 2009/068 20130101; A01D 34/6818 20130101; A01D 34/828
20130101; H01H 3/20 20130101; A01D 34/78 20130101 |
Class at
Publication: |
56/10.5 ;
56/11.9 |
International
Class: |
A01D 34/10 20060101
A01D034/10; H01M 14/00 20060101 H01M014/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 14, 2011 |
JP |
2011-132155 |
Claims
1. An electric lawn mower comprising: a mower body including an
electric motor, a cutting blade rotatably driven by the electric
motor for mowing a lawn, a switch assembly including a first
switch, a second switch and a main switch; wherein: the electric
motor is started when the main switch is turned on; the first
switch includes a first actuator; and the second switch includes a
second actuator, such that when the switch assembly is operated
according to a proper operation sequence, in which the second
switch is moved to an on-operation position after the first switch
is moved to an on-operation position, the first actuator and the
second actuator interact with each other to activate the main
switch, and when the switch is operated according to an improper
operation sequence, in which second switch is moved to the
on-operation position before the first switch is moved to the
on-operation position, the first actuator and the second actuator
do not interact with each other, so that the main switch is not
activated.
2. The electric lawn mower according to claim 1, wherein the mower
body further includes a battery mount configured to mount a
battery, and the electric motor is driven by electric power from
the battery.
3. The electric lawn mower according to claim 1, wherein: the first
switch further includes a first interference avoidance projection,
and the second switch further includes a second interference
avoidance projection such that when the switch assembly is operated
according to the improper operation sequence, the first
interference avoidance projection and the second interference
avoidance projection contact each other to prevent the first switch
from moving to the on-operation position, so that the first
actuator and the second actuator do not interact with each
other.
4. The electric lawn mower according to claim 1, wherein the switch
further includes a switch cover configured to prevent an
unintentional operation of at least one of the first switch and the
second switch.
5. An electric lawn mower comprising: a mower body including an
electric motor, a cutting blade rotatably driven by the electric
motor for mowing a lawn, a switch assembly including a first
switch, a second switch and a n switch; wherein: the first switch
is movable between an off-operation position and an on-operation
position in a first direction; the second switch is movable between
an off-operation position and an on-operation position in a second
direction: the main switch is turned on when the second switch has
moved from the off-operation position to the on-operation position
after the first switch has moved from the off-operation position to
the on-operation position; a stopper assembly configured to prevent
the first switch from moving from the off-operation to the
on-operation position after the second switch has moved from the
off-operation position to the on-operation position when the first
switch is positioned at the off-operation position.
6. The electric lawn mower according to claim 5, wherein the
stopper assembly comprises a first stopper provided on the first
switch and a second stopper provided on the second switch, the
first stopper and the second stopper are positioned to oppose each
other in the first direction when the first switch is positioned at
the off-operation position and the second switch is positioned at
the on-operation position.
7. The electric lawn mower according to claim 6, wherein the first
stopper and the second stopper are projections projecting from the
first switch and the second switch, respectively.
8. The electric lawn mower according to claim 6, wherein the first
switch moves linearly in the first direction and the second switch
pivots in the second direction about a pivot axis that is parallel
to the first direction.
9. The electric lawn mower according to claim 5, wherein the switch
assembly further includes a switch cover configured to prevent an
unintentional operation of at least one of the first switch and the
second switch.
10. The electric lawn mower according to claim 5, wherein the mower
body further includes a battery mount configured to mount a
battery, and the electric motor is driven by electric power from
the battery.
11. The electric lawn mower according to claim 1, wherein the first
switch is a cylindrical push-button switch and the second switch is
a pivotable lever-type switch, and wherein the first actuator and
the second actuator each include an elongated arm that projects
towards the main switch such that when the switch assembly is
operated according to the proper operation sequence a leading edge
of the first actuator elongated arm contacts the main switch to
start the electric motor.
12. The electric lawn mower according to claim 5, wherein the first
switch is a cylindrical push-button switch and the second switch is
a pivotable lever-type switch, and wherein the first switch and the
second switch each include an elongated arm that projects towards
the main switch such that when the switch assembly is operated
according to a proper operation sequence a leading edge of the
first switch elongated arm contacts the main switch to start the
electric motor.
13. An electric lawn mower comprising: a mower body including an
electric motor, a cutting blade rotatably driven by the electric
motor for mowing a lawn, a switch assembly including a first
switch, a second switch and a main switch, wherein: the first
switch is movable between an off-operation position and an
on-operation position in a first direction; the second switch is
movable between an off-operation position and an on-operation
position in a second direction; and the main switch is turned on
when the second switch has moved from the off-operation position to
the on-operation position after the first switch has moved from the
off-operation position to the on-operation position.
14. The electric lawn mower according to claim 13, further
comprising a stopper assembly configured to prevent the first
switch from moving from the off-operation to the on-operation
position after the second switch has moved from the off-operation
position to the on-operation position when the first switch is
positioned at the off-operation position.
15. The electric lawn mower according to claim 14, wherein the
stopper assembly comprises a first stopper provided on the first
switch and a second stopper provided on the second switch, the
first stopper and the second stopper are positioned to oppose each
other in the first direction when the first switch is positioned at
the off-operation position and the second switch is positioned at
the on-operation position.
16. The electric lawn mower according to claim 15, wherein the
first stopper and the second stopper are projections projecting
from the first switch and the second switch, respectively.
17. The electric lawn mower according to claim 13, wherein the
first switch moves linearly in the first direction and the second
switch pivots in the second direction about a pivot axis that is
parallel to the first direction.
18. The electric lawn mower according to claim 13, wherein the
switch assembly further includes a switch cover configured to
prevent an unintentional operation of at least one of the first
switch and the second switch.
19. The electric lawn mower according to claim 13, wherein the
first switch is a cylindrical push-button switch and the second
switch is a pivotable lever-type switch, and wherein the first
switch and the second switch each include an elongated arm that
projects towards the main switch such that when the switch assembly
is operated according to a proper operation sequence a leading edge
of the first switch elongated arm contacts the main switch to start
the electric motor.
20. The electric lawn mower according to claim 13, wherein the
mower body further includes a battery mount configured to mount a
battery, and the electric motor is driven by electric power from
the battery.
Description
[0001] This application claims priority to Japanese patent
application serial number 2011-132155, the contents of which are
incorporated herein by reference.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] Embodiments of the present invention relate to electric lawn
mowers that may be used outdoors for mowing grass or the like.
[0004] 2. Description of the Related Art
[0005] Known lawn mowers generally include a mower body and a
handle. The mower body is typically provided with wheels. The
handle extends obliquely upward in a rearward direction from the
mower body. The user may grasp the handle and push the mower body
to move the same for performing a lawn mowing operation. The mower
body may have a cutting blade that is rotatably driven by an
electric motor as a drive source. In general, the motor is disposed
within the mower body with its axis oriented in the vertical
direction. The cutting blade rotates within a horizontal plane
about the motor axis at a position along the lower surface of the
mower body. Therefore, changing the vertical position of the wheels
relative to the mower body can change the cutting height or the
mowing height. EP0829196A2 (also published as Japanese Patent No.
3160759 and U.S. Pat. No. 5,910,091), U.S. Pat. No. 5,806,374 (also
published as Japanese Patent No. 3329654), U.S. Pat. No. 5,736,837
(also published as Japanese Patent No. 3553277) and EP1285568A1
(also published as Japanese Patent No. 3776772 and U.S. Pat. No.
6,658,829) teach various techniques regarding electric lawn
mowers.
[0006] In addition to electric lawn mowers driven by an AC power
source, there have been proposed DC powered electric lawn mowers
that can use batteries serving as DC power sources. When a DC
powered electric lawn mower is used, the user does not need to lug
a long power cord, and therefore, the performance (usability) in
handling the lawn mower outdoors may be improved and the mowing
operation can be efficiently performed. The battery may be removed
from the tool body for recharging by a battery charger, so that the
battery can be repeatedly used.
[0007] In recent years, battery packs having a battery case and a
plurality of lithium-ion battery cells disposed within the battery
case have been broadly used as batteries for power tools, etc.
Therefore, there have been proposed electric lawn mowers having
lithium-ion battery packs as power sources.
[0008] In this kind of battery powered electric lawn mower, there
has been proposed various techniques for preventing accidental
starting of the electric motor. For example, there has been
proposed a mechanism called a lock-off mechanism that includes a
first switch member and a second switch member disposed on a
handle. The electric motor may not be started unless these switches
are operated according to a given operation sequence. However, this
mechanism still requires durability improvements.
[0009] Therefore, there has been a need in the art for electric
lawn mowers that includes a switch device that is improved in
durability.
SUMMARY OF THE INVENTION
[0010] In one aspect according to the present teachings, an
electric lawn mower may include a switch device including a first
switch member, a second switch member and a main switch. A stopper
device may prevent a first switch member from moving from an
off-operation to an on-operation position (for turning on the main
switch after the second switch member has moved from an
off-operation position to an on-operation position).
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] FIG. 1 is a perspective view of an electric lawn mower
according to a representative example;
[0012] FIG. 2 is a vertical sectional view of a mower body of the
electric lawn mower showing a state where a battery is mounted and
a battery cover is closed;
[0013] FIG. 3 is a vertical sectional view of the mower body of the
electric lawn mower similar to FIG. 2 but showing a state where the
battery cover is opened and the battery is removed;
[0014] FIG. 4 is a plan view of the mower body of the electric lawn
mower;
[0015] FIG. 5 is a sectional view taken along line (V)-(V) in FIG.
4 and showing a lock-off key and a region around the lock-off
key:
[0016] FIG. 6 is a vertical sectional view of a switch device as
viewed in a direction indicated by arrow (VI) in FIG. 1;
[0017] FIG. 7 is a view showing the positional relationship between
primary components of the switch device as viewed in the same
direction as FIG. 6 and showing the state where both of first and
second switches are not operated to be turned on;
[0018] FIG. 8 is a front view of the switch device in the state
shown in FIG. 7 as viewed in a direction indicated by arrow (VIII)
in FIG. 7;
[0019] FIG. 9 is a front view of the switch device similar to FIG.
8 but showing the state where only the first switch has been
operated to be turned on;
[0020] FIG. 10 is a left side view of the switch device and showing
the state where only the second switch has been operated to be
turned on;
[0021] FIGS. 11(A) to 11(J) are plan views of examples of picture
indicator portions for a mowing height adjusting mechanism;
[0022] FIG. 12 is a perspective view of the electric lawn mower
having a battery converter mounted thereto;
[0023] FIG. 13 is a left side view of the electric lawn mower shown
in FIG. 12;
[0024] FIG. 14 is a vertical sectional view of the electric lawn
mower shown in FIG. 12; and
[0025] FIG. 15 is a perspective view of the battery converter.
DETAILED DESCRIPTION OF THE INVENTION
[0026] Each of the additional features and teachings disclosed
above and below may be utilized separately or in conjunction with
other features and teachings to provide improved electric lawn
mowers. Representative examples of the present invention, which
examples utilize many of these additional features and teachings
both separately and in conjunction with one another, will now be
described in detail with reference to the attached drawings. This
detailed description is merely intended to teach a person of skill
in the art further details for practicing preferred aspects of the
present teachings and is not intended to limit the scope of the
invention. Only the claims define the scope of the claimed
invention. Therefore, combinations of features and steps disclosed
in the following detailed description may not be necessary to
practice the invention in the broadest sense, and are instead
taught merely to particularly describe representative examples of
the invention. Moreover, various features of the representative
examples and the dependent claims may be combined in ways that are
not specifically enumerated in order to provide additional useful
examples of the present teachings. Various examples will now be
described with reference to the drawings.
[0027] In one example, an electric lawn mower may include a mower
body including an electric motor and a cutting blade rotatably
driven by the electric motor for mowing a lawn. A switch device may
include a first switch member, a second switch member and a main
switch. The electric motor may be started when the main switch is
turned on. The first switch member may include a first actuation
member. The second switch member may include a second actuation
member. When the switch device is operated according to a proper
operation sequence the first actuation member of the first switch
member and the second actuation member of the second switch member
interact with each other to turn on the main switch. The second
switch member is moved to an on-operation position after the first
switch member is moved to an on-operation position. When the switch
device is operated according to an improper operation sequence,
however, the second switch member is moved to the on-operation
position before the first switch member is moved to the
on-operation position. In this situation, the first actuation
member of the first switch member and the second actuation member
of the second switch member do not interact with each other.
Therefore, the main switch is not turned on.
[0028] The first actuation member and the second actuation member
do not interact with each other for turning on the main switch when
the switch device is operated according to the improper operation
sequence. In this way, it is possible to prevent or minimize
potential damage to the first and second actuation members even in
the undesirable situation where the handle of the mower has been
unintentionally moved to an operation position.
[0029] The mower body may further include a battery mount device
configured to be able to mount a battery. The electric motor may be
driven with a supply of an electric power from the battery.
[0030] The first switch member may further include a first
interference avoidance member, and the second switch member may
further include a second interference avoidance member. When the
switch device is operated according to the improper operation
sequence, the first interference avoidance member and the second
interference avoidance member interact with each other to prevent
the first switch member from moving to the on-operation position,
so that the first actuation member and the second actuation member
do not interfere with each other. With this arrangement, even in
the case that the first main switch has been forcibly operated, no
large force will be applied to the first and second actuation
members, so that potential damage to the first and second actuation
members may be prevented or minimized. Therefore, the durability of
the switch device may be improved. The switch device may further
include a switch cover configured to prevent unintentional
operation of at least one of the switch members. With this
arrangement, unintentional operation of the first switch member
and/or the second switch member may be prevented by the switch
cover. Furthermore, it is possible to prevent intentional operation
of the electric motor or other related components.
[0031] Referring to FIG. 1, an entire view of an electric lawn
mower 1 is shown. The electric lawn mower 1 generally includes a
mower body 10 and a handle 3. The mower body 10 is preferably
provided with two front and rear pairs of left and right wheels 2.
The mower body 10 further preferably includes a storage box 4
disposed on the rear side for storing mowed lawn grass, etc. The
handle 3 has a shape like a frame and extends diagonally upward in
the rearward direction from the rear portion of the mower body 10,
so that the handle 3 extends over the storage box 4. Therefore, in
order to perform a lawn mowing operation, the user may be
positioned on the rear side of the lawn mower 1, grasp the handle 3
and push the lawn mower 1 forward. The handle 3 is pivotally joined
to the rear portion of the mower body 10. Left and right fixing
screws 3a can fix the pivoted position of the handle 3. Therefore,
the handle 3 can pivot forward so as to be folded over the mower
body 10 by loosening the left and right fixing screws 3a. In the
following description, left and right directions with respect to
parts and constructions of the lawn mower 1 mean the left and right
directions as viewed from the perspective of the user who operates
the lawn mower 1.
[0032] As shown in FIGS. 2 and 3, the mower body 10 may include a
deck portion 11 and a cowling portion 12. The deck portion 11
supports the wheels 2. The cowling portion 12 is preferably mounted
to the deck portion 11 for covering the upper side of the deck
portion 11. An electric motor 13 may be mounted to the deck portion
11 at substantially the central position of the deck portion 11.
More specifically, the electric motor 13 is preferably mounted to
the deck portion 11 in a downwardly oriented position with its
output shaft 13a oriented towards a ground surface G (i.e., with
its motor axis J oriented substantially perpendicular to the ground
surface G).
[0033] The deck portion 11 is preferably provided with a
grass-collecting duct 17 for collecting grass mowed by a cutting
blade 14. The lower side of the deck portion 11 is preferably
concaved upward to define a substantially cylindrical
grass-collecting opening 17a of the grass-collecting duct 17. The
grass-collecting opening 17a is preferably opened in a wide manner
towards the ground surface G. A cutting blade 14 is preferably
positioned within the grass-collecting opening 17a and extends
within a substantially horizontal plane. The grass-collecting duct
17 defines a passage having a spiral shape about the axis of the
electric motor 13 and extending rearward from the front portion of
the grass collecting-opening 17a toward the rear side such that the
depth of the passage in the upward direction becomes deeper toward
the rear side. The rear end of the passage communicates with a
widely opened discharge port 17b positioned at the rear portion of
the mower body 10. The grass-collecting box 4 is preferably
connected to the discharge port 17b.
[0034] The output shaft 13a of the electric motor 13a preferably
protrudes downward from the lower side of the deck portion 11. The
cutting blade 14 is preferably mounted to the downwardly protruding
portion of the output shaft 13a. Therefore, the cutting blade 14
rotates about the output shaft 13a within a substantially
horizontal plane along the lower side of the deck portion 11. The
height of the cutting blade 14 measured from the ground surface G
corresponds to the mowing height of the lawn. In this example, the
mowing height can be adjusted by a mowing height adjusting device
15. To this end, the wheels 2 are preferably supported on the deck
portion 11 such that the wheels 2 can be moved vertically relative
to the deck portion 11. As shown in FIG. 4, the mowing height
adjusting device 15 may be provided with a mowing height adjusting
lever 18 that can be pivoted forwards and backwards by the user.
The lever 18 is coupled to the wheels 2 via a link mechanism 16, so
that the vertical position of the wheels 2 can be changed according
to the pivoted position of the lever 18. Hence, it is possible to
adjust the vertical height of the cutting blade 14 from the ground
surface G.
[0035] Electric power from a battery or batteries can be used to
operate the electric lawn mower 1. To this end, a battery mount
device 20 is preferably disposed at substantially centrally of the
upper surface of the mower body 10, or more specifically the upper
surface of the cowling portion 12. The battery mount device 20
preferably has a battery cover 22 and a battery mount base 23. The
battery cover 22 may be opened and closed as it is pivoted upward
and downward. As shown in FIG. 3, when the battery cover 22 is
pivoted upward to be opened, the battery mount base 23 may be
exposed to the outside. In this example, the battery mount base 23
is configured to be able to mount only one battery 21. When the
battery cover 22 is pivoted downward and closed, the battery mount
base 23 and the battery 21 mounted thereto may be covered entirely
by the battery cover 22. A cord insertion hole 22b may be formed in
the rear portion of the battery cover 22 for allowing passage of a
power cord 53 of a battery converter 50 that will be described
later.
[0036] A lithium-ion battery generally used for a battery powered
electric tool, such as an electric screwdriver or an electric
circular saw, may be used as the battery 21. In this example, the
battery 21 is of a slide-mount type as will be hereinafter
described. As shown in FIG. 4, a pair of left and right slide rails
23a are preferably mounted to the battery mount base 23. The
battery 21 is configured to be able to slide on the slide rails 23a
in the forward direction for mounting to the battery mount base 23
and in the rearward direction for removing from the battery mount
base 23. A connector 24 may be mounted to the battery mount base 23
at a position between the slide rains 23a. When the battery 21 is
slid forward on the slide rails 23a to reach the mount position,
the battery 21 is electrically connected to a power source circuit
(not shown) of the mower body 10 via the connector 24.
[0037] As indicated by an outline arrow in FIG. 3, in this example,
a mounting direction for mounting the battery 21 to the battery
mount base 23 is set to be declined in the forward direction. Thus,
the surface of the battery mount base 23 is also declined in the
forward direction.
[0038] As shown in FIG. 2, when the battery 21 is at the mount
position on the battery mount base 23, the battery 21 is positioned
generally above the electric motor 13 and rearward of the motor
axis J (obliquely upward in the rearward direction). In addition,
the battery 21 in the mount position is not directly opposite the
motor axis J of the electric motor 13 in the vertical direction. In
other words, the battery 21 at the mount position is preferably
displaced a certain amount from the electric motor 13 as viewed in
a plan view.
[0039] As described above, because the battery 21 is mounted to the
mount base 23 at a position displaced rearward of the electric
motor 21, the vertical height of the mower body 10 can be
minimized. In addition, because the mounting direction of the
battery 21 is inclined relative to the motor axis. From a user's
perspective, the battery 21 at the mount position is declined with
its rear end positioned at a height above its front end. Therefore,
the mounting and removing operations of the battery 21 can be
easily performed.
[0040] Further, because the battery mount base 23 is disposed at
the upper surface of the cowling portion 21, the battery mount base
23 is separated from the deck portion 11 to which the electric
motor 13 is mounted. In other words, the battery mount base 23 is
not provided directly on the deck portion 11. Therefore, vibrations
of the electric motor 13 may not be directly transmitted to the
battery 21. Hence, the electric lawn mower 1 is prepared for any
potential effects by vibrations to the battery 21 and its related
connections.
[0041] A lock claw 21a for locking the battery 21 at the mount
position relative to the battery mount base 23 and a release button
(not shown) for releasing the lock condition caused by the lock
claw 21a are preferably provided on the rear portion of the battery
21. The release button may be positioned at the rear end surface of
the battery 21. The positional relationship between the release
button and an uppermost portion 10a of the mower body 10 (more
specifically, the cowling portion 12) is determined such that the
release button is preferably positioned at a level higher than the
uppermost portion 10a when the battery 21 is positioned at the
mount position to the battery mount base 23. With this arrangement,
the operation for releasing the lock condition of the battery 21
can be easily performed. In this example, the uppermost portion 10a
of the mower body 10 corresponds to an upper portion of the
discharge port 17b of the grass-collecting duct 17.
[0042] As shown in FIG. 4, water drain holes 25 may be formed in
the left and right side regions of the front portion, i.e., the
lowest portion, of the battery mount base 23 that is declined in
the forward direction. The left and right water drain holes 25 are
preferably displaced from the electric motor 13 as viewed in the
plan view of FIG. 4 so as not to be opposed to the electric motor
13 in the vertical direction. Therefore, if water accidentally
reaches the battery mount base 23, such water may be collected at
the lowermost position of the battery mount base 23 and then may be
discharged toward the side of the deck portion 11 via the water
drain holes 25. Because the water drain holes 25 are displaced from
the electric motor 13, water discharged downwardly from the water
drain holes 25 may be prevented from being poured to the electric
motor 13. Therefore, it is possible to ensure that the electric
motor 13 is protected from outside water.
[0043] Further, as shown in FIGS. 2 and 3, a water-preventing rib
26 is preferably formed in the mower body 10 at a position on the
front side of the battery mount base 23 and extending upwards
therefrom. The water-preventing rib 26 preferably has a
substantially semicircular-arc shape that expands forward as viewed
in the plan view. When the mower body 10 is at an upright position,
the water-preventing rib 26 may extend upward above the battery
mount base 23. Should rain water or the like accidentally enter the
inside of the battery cover 22 in the closed position (via a
potential clearance that may be formed between the battery cover 22
and the mower body 10), the water-preventing rib 26 may prevent
such water from directly leaking to the battery mount base 23.
[0044] A key insertion portion 31 for inserting a lock-off key 30
may be formed on the mower body 10 at a position on the right side
of the battery mount base 23. In other words, the key insertion
portion 31 may be positioned on the side opposite the mowing height
adjusting lever 18 with respect to the center of the mower body 10.
More specifically, the position of the key insertion portion 31 is
preferably chosen to be on the right side of the battery 21, so
that the key insertion portion 31 does not intervene in the
movement path of the battery 21. The battery 23 typically moves
along the movement path when it is mounted to and removed from the
battery mount base 23 of the battery mount device 20.
[0045] The lock-off key 30 may be used for releasing a lock-off
state. A lock-off state is the state where the battery 21 is
electrically disconnected to the power source circuit and no
electric power is supplied to the electric motor 13 of the mower
body 10. Therefore, the electric motor 30 may not be started even
in the event that the user operates a start switch. In order to
release the lock-off state, the user may insert the lock-off key 30
into the key insertion portion 31 and turn it to the right or left,
so that the battery 21 may be electrically connected to the power
source circuit. In this way, the lock-off key 30 can be used for
maintaining or releasing the lock-off state of the electric motor
13.
[0046] The key insertion portion 31 is positioned within a range
that can be covered by the battery cover 22. Therefore, the key
insertion portion 31 and the lock-off key 30 can be prevented from
being getting wet.
[0047] As shown in FIG. 5, a restricting projection 22a is
preferably formed integrally with the inner surface of the battery
cover 22. The restricting projection 22a may be positioned directly
above the lock-off key 30 when the battery cover 22 is closed.
Therefore, the restricting projection 22a can prevent accidental
removal of the lock-off key 30 due to vibrations or the like. As
the battery cover 22 is opened, the restricting projection 22a
moves upwardly away from the lock-off key 30, so that the user can
remove the lock-off key 30 from the key insertion portion 31.
[0048] As shown in FIG. 4, the lock-off key 30 may be provided with
a knob portion 30a having a configuration like a generally flat
plate. The lock-off key 30 may be inserted into the key insertion
portion 31 with the surface of the knob portion 30a extending in
the forward and rearward directions. Therefore, the lock-off key 30
can be inserted into the key insertion portion 31 with a minimal
distance extending in the left and right directions. Hence, the
lock-off key 30 can be positioned close to the battery mount base
32. In addition, the width of the battery cover 22, with respect to
the left and right directions, can be minimized. The lock-off key
30 can be positioned inside the battery cover 22 when the battery
cover 22 is closed.
[0049] Further, positioning the lock-off key 30 close to the
battery mount base 32 enables the user to readily view the look-off
key 30 and the battery mount base 32 in one glance. Therefore, it
is possible to ensure that the battery 21 and the lock-off key 30
may not be accidentally left behind without being removed.
[0050] As shown in FIG. 4, a carrying handle 27 is preferably
attached to the uppermost portion 10a of the mower body 10 on the
rear side of the battery mount base 23. The carrying handle 27 can
be grasped by the user for carrying the electric lawn mower 1. A
lock claw (not shown) for locking the battery cover 22 at a close
position and a release lever 28 for releasing the lock condition of
the battery cover 22 at the close position may be disposed at the
rear portion of the battery mount base 23 on the front side of the
carrying handle 27. Further, a pair of left and right legs 29 are
preferably provided on the rear portion of the mower body 10. By
using these legs 29, the mower body 10 can be self-supported in an
upright position, so that the electric lawn mower 1 can be stored
with the mower body 10.
[0051] A dual operation switch device 40 is preferably mounted to
the right side of the handle 3 and is shown in detail in FIG. 6.
The switch device 40 preferably includes a first switch member 41
of a push-button type, a second switch member 42 of a lever-type,
and a main switch 43. The first switch member 41, the second switch
member 42 and the main switch 43 are preferably disposed within a
switch case 44 that is mounted to the right side of the handle 3 at
a position enabling the user to easily operate the switch device
40. Within the switch case 44, the second switch member 42 is
preferably positioned on the lower side of the first switch member
41, and the main switch 43 is preferably positioned in front of the
first switch member 41.
[0052] The first switch member 41 is preferably configured as a
cylindrical push button and is preferably supported within the
switch case 44 so as to be movable in a direction perpendicular to
the sheet surface of FIG. 6 (i.e., left and right direction). The
first switch member 41 preferably has a head that protrudes
leftward through the left side wall of the switch case 44. The
lower side of the head is covered by a switch cover 49 that has a
substantially semicircular cross-section and is preferably
integrally formed with the left side wall of the switch case 44.
The switch cover 49 can prevent the first switch member 41 from
being unintentionally operated due to unintentional contact with
the user's hand or other objects.
[0053] The first switch member 41 may be spring-biased toward an
off position that is positioned on the front side with respect to
the sheet surface of FIG. 6. The first switch member 41 may be
moved to an on-operation position when the user pushes the first
switch member 41 into the switch cover 49 with his or her finger
against the biasing force.
[0054] The second switch member 42 is preferably vertically
pivotally supported by a support rod 42c within the switch case 44.
The rear end of the second switch member 42 is preferably connected
to one end of a switch lever 45. The switch lever 45 preferably
extends rearward through the rear wall of the switch case 44 and is
bent to the left along a grip portion 3b of the handle 3. The other
end of the switch lever 45 is preferably vertically pivotally
joined to the left side part of the handle 3 via a pivotal support
46. With this construction, the user can operate the second switch
member 42 between an on and an off position. In this example, the
second switch member 42 is moved to the on-operation position as
the switch lever 45 is pivoted downward, and the second switch
member 42 is moved to the off-operation position as the switch
lever 45 is pivoted upward. A tension spring 48 preferably biases
the switch lever 45 toward a position where the second switch
member 42 is positioned at the off-operation position.
[0055] The main switch 43 has an operation button 43a that is
preferably spring-biased toward an off position. A known
microswitch may be used as the main switch 43. In this example, the
main switch 43 is fixed within the switch case 44 in such a state
that the operation button 43a is oriented downward. Therefore, as
the operation button 43a is pushed upward into the switch case 44,
the main switch 43 is turned on to output an on signal that is
transmitted to the power source circuit of the mower body 10 via a
wire 47.
[0056] The switch device 40 of this example has a lock-off function
that confirms the operation of the second switch member 42 for
turning on the main switch 43 only after the first switch member 41
has been operated to move to the on-operation position. According
to this lock-off function, the first switch member 41 cannot be
operated to be moved to the on-operation position if the second
switch member 42 has already been operated to be moved to the
on-operation position. Therefore, the main switch 43 may be held in
the off state. As a result, it is possible to prevent the electric
motor 13 from being accidentally started. In the following
description, an operation sequence, in which the second switch
member 42 is moved to the on-operation position after the first
switch member 41 has moved to the on-operation position, will be
called a "proper operation sequence". An operation sequence, in
which the second switch member 42 is operated to be moved to the
on-operation position before the first switch member 41 has moved
to the on-operation position, will be called an "improper operation
sequence." In this way, the switch device 40 uses the lock-off
function to allow the electric motor 13 to be started if the first
and second switch members 41 and 42 are operated according to the
proper operation sequence. Conversely, it may inhibit the electric
motor 13 from starting if the first and second switch members 41
and 42 are operated according to the improper operation
sequence.
[0057] As shown in FIGS. 6 and 7, a first actuation member 41a may
be formed integrally with the lower portion of the cylindrical side
surface of the first switch member 41. It may extend forward toward
the main switch 43 from the lower portion of the cylindrical side
surface. A first interference avoidance member 41b may be formed on
or mounted to the lower portion of the cylindrical side surface of
the first switch member 41. It is preferably located at a position
on the rear side of the base portion of the first actuation member
41a. The first interference avoidance member 41b is preferably
formed to have a shape protruding downward at an angle from the
lower portion of the cylindrical side surface.
[0058] A second actuation member 42a may be formed integrally with
the front end of the second switch member 42 and extends forward to
have a leading end positioned below the main switch 43. A second
interference avoidance member 42b may be formed integrally with the
upper surface of the base portion of the second actuation member
42a. The second interference avoidance member 42b may have a shape
protruding at an upward angle.
[0059] FIGS. 6 to 8 show non-operational states where both of the
first switch member 41 and the second switch member 42 are not in
the on-operation positions. In this non-operational state, the
first actuation member 41a of the first switch member 41 is held at
a position that is located to the left of the second actuation
member 42a of the second switch member 42. It is also preferably
located to the left of the area between the leading end of the
second actuation member 42a and the operation button 43a of the
main switch 43.
[0060] In this non-operational state, if the first switch member 41
is moved to the on-operation position according to the proper
operation sequence, the first actuation member 41a may intervene in
the path of movement of the second actuation member 42a.
Thereafter, if the second switch member 42 is operated to be moved
to the on-operation position, the first actuation member 41a may be
pushed upward, as viewed in FIG. 9, so that the operation button
43a of the main switch 43 is pushed to move to the on position by
the first actuation member 41a. When the main switch 43 is turned
on by the operation of the second operation switch 42 to the
on-operation position, the main switch 43 outputs an on signal that
is supplied to the mower body 10 via the wire 47 to start the
electric motor 13.
[0061] Conversely, if the second switch member 42 is operated to be
moved to the on-operation position when the first switch member 41
is positioned at the off-operation position (according to the
improper operation sequence), the leading end of the second
actuation member 42a may pivot idly and may not reach the operation
button 43a of the main switch 43. Therefore, the main switch 43 may
not be turned on.
[0062] In addition, if the first switch member 41 is operated to
move toward the on-operation position after the second switch
member 43 has moved to the on-operation position, the first
interference avoidance member 41b of the first switch member 41 may
contact the second interference avoidance member 42b of the second
switch member 42 as shown in FIG. 10. In this way, the first switch
member 41 cannot be pushed further toward the on-operation
position. Because the first interference avoidance member 41b
contacts the second interference avoidance member 42b to prevent
the first switch member 41 to be pushed to reach the on-operation
position, it is possible to avoid potential interference of the
first actuation member 41a with the second actuation member 42a of
the second switch member 42.
[0063] The first interference avoidance member 41b and the second
interference avoidance member 42b may both have a relatively high
mechanical strength due to their configuration and may be able to
resist a relatively large external force. Therefore, contact or
interference between the first interference avoidance member 41b
and the second interference avoidance member 42b may avoid
interference between the first actuation member 41a and the second
actuation member 42a. The first actuation member 41a and the second
actuation member 42b are preferably configured to be elongated like
an aim with relatively low mechanical strength in comparison to the
first and second interference avoidance members 41b and 42b.
Therefore, even in the event that the user has forcibly pushed the
first switch member 41 toward the on-operation position with a
large force according to the improper operation sequence, such a
large force may not be applied to the first and second actuation
members 41a and 42a. Hence, it is possible to avoid potential
damage to the first and second actuation members 41a and 42a. This
can improve the durability of the switch device 40. Although FIG.
10 shows that the leading end of the first actuation member 41a is
overlapping with the leading end of the second actuation member 42a
as viewed from the front side with respect to the sheet of FIG. 10,
the leading end of the first actuation member 41a is spaced from
the leading end of the second actuation member 42a in the direction
perpendicular to the sheet surface of FIG. 10 (i.e., the left and
right direction). Therefore, in the state shown in FIG. 10, the
leading ends of the first and second actuation members 41a and 42a
are actually not in contact with each other.
[0064] When the first switch member 41 is moved to the on-operation
position in accordance with the proper operation sequence, the
first interference avoidance member 41b preferably moves across the
moving path of the second interference avoidance member 42b of the
second switch member 42 to a position out of the moving path.
Therefore, the second interference avoidance member 42b preferably
does not contact the first interference avoidance member 41b if the
second switch 41 is subsequently moved to the on-operation
position. The positions of the first interference avoidance member
41b and the second interference avoidance member 42b can be taken
at various locations where the first switch member 41 and the
second switch member 42 are operated to be moved to the
on-operation positions or the off-operation positions so as to
determine appropriate positions of the elements.
[0065] Next, as shown in FIGS. 1 and 4, the height adjusting device
15 for adjusting the mowing height is preferably disposed at the
left side portion of the mower body 10. As described previously,
forward and rearward pivoting of the mowing height adjusting lever
18 can change the vertical position of the wheels 2 via the link
mechanism 16. In this way, the height of the mower body 10 relative
to the ground surface G can be changed so that the vertical height
of the cutting blade 14 relative to the ground surface G (i.e., the
mowing height) can be appropriately set.
[0066] An indicator for displaying the mowing height by way of a
scale and/or a group of pictures may be provided on the lateral
side of the lever 18. As shown in FIG. 4, the lever 18 extends
preferably upward from within the cowling portion 12 through an
insertion opening 19 formed in the cowling portion 12. A scale
indicator portion 61 is preferably provided on the surface of the
cowling portion 12 at a position on the left side (lower side as
viewed in FIG. 4) of the insertion opening 19. The scale indicator
portion 61 preferably includes scale marks and corresponding
numerals indicative of the mowing height. A picture indicator
portion 60 is preferably provided on the surface of the cowling
portion 12 at a position on the right side (upper side as viewed in
FIG. 4) of the insertion opening 19. The picture indicator portion
60 is preferably configured to indicate the cowling height mainly
by pictures such as those of lawn grass. The picture indicator
portion 60 may be molded onto the upper surface of the cowling
portion 12.
[0067] FIGS. 11(A), 11(B), 11(C), 11(D) and 11(E) show various
examples of the picture indicator portion 60. In each example, the
mowing height is preferably indicated by pictures on a scale of one
to ten within a range of between 15 mm and 70 mm, and the pictures
are arranged so that the indicated mowing height becomes gradually
smaller from the leftmost picture to the rightmost picture. In
other words, the mowing amount (length) of the lawn grasses becomes
gradually larger from the leftmost picture to the rightmost
picture. According to the example shown in FIG. 11(A), a picture
indicator portion 60A preferably includes numerals on the upper
side of the figures for indicating numerical values of the mowing
heights indicated by the corresponding figures. However, in this
example, the numerical values for the moving heights of 25 mm, 35
mm and 45 mm are replaced with dots. According to the example shown
in FIG. 11(B), a picture indicator portion 60B preferably includes
the numerical values of the moving heights, which are marked in the
corresponding figures. Also in this example, the numerical values
for the moving heights of 25 mm, 35 mm and 45 mm are replaced with
dots. A picture indicator portion 60C shown in FIG. 11(C) is
similar to the picture indicator portion 60B in that the numerical
values for the moving heights are marked in the corresponding
figures. The picture indicator portion 60C is different from the
picture indicator portion 60B in that the numerical values for the
moving heights of 25 mm, 35 mm and 45 mm are included but are
marked with numerals that are smaller in size than the numerals
used for the other moving heights.
[0068] A picture indicator portion 60D according to the example
shown in FIG. 11(D) is similar to the picture indicator portion 60A
in that the numerical values of the mowing heights are marked on
the upper side of the figures for indicating numerical values of
the mowing heights. The picture indicator portion 60D is different
from the picture indicator portion 60A in that the configurations
of the upper portions of the grasses indicated by the figures are
more roughly drawn in comparison with those of the picture
indicator portions 60A to 60C. A picture indicator portion 60E
shown in FIG. 11(E) is similar to the picture indicator portion 60B
in that the numerical values of the moving heights are marked in
the corresponding figures. However, the configurations of the upper
portions of the grasses indicated by the figures are roughly drawn
as in the case of the picture indicator portion 60D. Any one of the
picture indicator portions 60A to 60D may be selectively used for
the picture indicator portion 60 for visually indicating the change
of the mowing height along the moving direction of the lever 18.
Therefore, the user can intuitively recognize the mowing condition
based on the visual image, so that the operability of the electric
lawn mower 1 can be further improved. For example, manufacturer of
lawn mowers may select any one of the picture indicator portions
60A to 60C to suit the needs or preferences of the user.
[0069] FIGS. 11(F), 11(G), 11(H), 11(I) and 11(J) show further
examples of the picture indicator portion 60. In each example shown
in FIGS. 11(F) to 11(J), the mowing height is preferably indicated
by pictures on a scale of one to six within a range that may
similar to that of FIGS. 11(A) to 11(E). Pictures indicating the
mowing heights in a picture indicator portion 60F are mountains
that compare the mowing heights to heights of the mountains.
Pictures indicating the mowing heights in a picture indicator
portion 60G are grasses and scissors that cut the grass at
different heights. Pictures indicating the mowing heights in a
picture indicator portion 60H may be illustrations of lengths of
grass before and/or after cutting. Pictures indicating the mowing
heights in a picture indicator portion 60I are grasses with
illustration of cutting blades and lengths of grasses before and
after cutting. Pictures indicating the mowing heights in a picture
indicator portion 60J are grasses with illustration of cutting
blades and lengths of grasses after cutting.
[0070] Although the picture indicator portions 60A to 60E are
designed suitable for molding onto the upper surface of the cowling
portion 12 along the lever insertion opening 19, the picture
indicator portions 60F to 60J may be directly printed on the upper
surface of the cowling portion 12 along the lever insertion opening
19. Alternatively, the picture indicator portions 60F to 60J may be
printed on labels that can be put on the upper surface of the
cowling portion 12.
[0071] By visualizing the mowed heights by using figures in
addition to or in place of a scale as described above, the user can
readily determine the mowing condition at one glance. Therefore,
the operability of the electric lawn mower 1 is also improved in
this respect.
[0072] The electric lawn mower 1 of this example is preferably
configured to use a battery converter 50 shown in FIG. 15 as a
power source in place of the battery 21 mounted to the upper
portion of the mower body 10. The battery converter 50 preferably
includes a converter body 51 and an adapter 52. Two batteries (not
shown) may be stored within the converter body 51. The adapter 52
may be designed to be capable of being mounted to the battery mount
device 20. The converter body 51 and the adapter 52 may be
electrically connected to each other via a power cord 53. The
converter body 51 preferably has a case 51a and a lid 51b for
opening and closing the case 51a. The two batteries are preferably
stored within the case 51a and can be removed from the case 51a by
opening the lid 51b. A hook 55 is preferably provided on the
backside surface of the case 51a.
[0073] In this example, the battery converter 50 may be a battery
converter usable for the other type of power tool than the lawn
mower. For example, the other type of power tool may include a
hedge trimmer and a high-pressure water sprayer, which may be
mainly used outdoors or for gardening. The adapter 52 may be
mounted to the battery mount device 20 in place of the battery 20
that is a single battery. The hook 55 of the converter body 51 may
be hooked to a waist belt (not shown) that may be worn by the user.
Therefore, the user can carry the converter body 51 having two
batteries stored therein. Hence, the user can operate a power tool
that is reduced in weight, so that the operation efficiency can be
improved. Further, batteries having a low rating voltage can be
used for a power tool having a high rating voltage by connecting
the batteries in series. Therefore, batteries can be effectively
used even in the case that they have rating voltages different from
that of a power tool to be used. For example, by storing two
batteries each having a rating voltage of 18 V within the converter
body 51, these batteries can be used for a power tool having a
rating voltage of 36 V.
[0074] FIGS. 12 to 14 show states where the battery converter 50
may be mounted to the electric lawn mower 1. On the front side of
the battery cover 12, a pocket-like engaging member 54 for engaging
the hook 55 of the converter body 51 may be disposed on the upper
surface of the front portion of the mower body 10 at a position
substantially central with respect to the widthwise direction (left
and right direction). In this example, the engaging member 54 is
preferably formed integrally with the upper surface of the front
portion of the converter body 51. Therefore, with the hook 55 of
the converter body 51 engaged with the engaging member 54, the
converter body 51 can be held on the upper surface of the front
portion of the mower body 10 of the electric lawn mower 1. The
converter body 51 may have a relatively large weight because two
batteries are stored therein. Therefore, by positioning the
converter body 51 on the upper surface of the front portion of the
mower body 10 at the central position with respect to the widthwise
direction, it is possible to improve the ability of the electric
lawn mower 1 to move in a straight line. Hence, it is possible to
improve the operability and the workability of the electric lawn
mower 1.
[0075] As described previously the adapter 52 can be mounted to the
battery mount device 20 of the mower body 10. Therefore, the
adapter 52 may have a slide mounting structure similar to that of
the battery 21, so that the adapter 52 can be mounted to the
battery mount device 20 by being slid forward on the left and right
slide rails 23a of the battery mount base 23 and can be removed
from the battery mount device 20 by being slid rearward. Also, the
adapter 52 may have a lock claw (not shown) for locking the adapter
52 at the mount position relative to the battery mount base 23 and
may have a release button (not shown) for releasing the lock
condition of the lock claw.
[0076] The power cord 53 electrically connecting the converter body
51 and the adapter 52 preferably has a length that is sufficient to
connect the converter body 51 held at the front portion of the
mower body 10 to the adapter 52 mounted to the battery mount base
23. A cord insertion hole 22b may be formed in the rear portion of
battery cover 22, so that the power cord 53 may extend between
inside and outside of the battery cover 22 through the cord
insertion hole 22b. Two or more cord clips 56 may be attached to
the right side portion of the handle 3, so that the power cord 53
can be held to extend along the right side portion of the handle 3
by the cord clips 56. Therefore, unnecessary slack of the power
cord 53 can be eliminated so as not to hinder the mowing
operation.
[0077] The battery 21 may be a lithium-ion battery having a rating
voltage of 36 V, and the power source circuit and the electric
motor 13 may be configured to operate at 36 V. On the other hand,
as described previously, two batteries each having a rating voltage
of 18 V may be stored within the converter body 51 and may be
usable for a power tool having a voltage of 36 V. Also, these two
batteries may be lithium-ion batteries. Therefore, a battery
converter 50 may be used in place of the battery 21 for operating
the electric lawn mower 1. Therefore, if the battery 21 is removed
from the battery mount base 23 for recharging 18 V batteries
typically used in other power tools, such as electric screwdrivers,
can be moved to and used for operating the electric lawn mower
1.
[0078] With the above construction of the electric lawn mower 1,
the situation may occur where the switch device 40 has been
operated according to the improper operation sequence. In such a
situation, the first switch member 41 is pushed after the second
switch member 42 has been moved to the on-operation position. The
first interference avoidance member 41b of the first switch member
41 may then contact the second interference avoidance member 42b of
the second switch member 42. In this way, the pushing distance of
the first switch member 41 may be restricted to prevent the first
switch member 41 from reaching the on-operation position. Because
the first switch member 41 cannot reach the on-operation position,
it is possible to prevent interaction between the first actuation
member 41a and the second actuation member 42a. Therefore, even in
the event that the first switch member 41 is pushed by an
excessively large force during an improper operation sequence, the
first actuation portion 41a and the second actuation portion 42a
will not be activated. Hence, it may be possible to prevent
deformation of or damage to the first actuation member 41a and the
second actuation member 42a. Each extends like an arm and may be
easily deformed. In this way, it is possible to improve the
durability of the switch device 40.
[0079] In addition, the lower side of the head of the first switch
member 41 protruding from the switch case 44 may be covered by the
switch cover 49, so that first switch member 41 can be prevented
from being unintentionally operated.
[0080] The above example can be modified in various ways. For
example, although the first switch member 41 is of a push-button
type and the second switch 42 is of pivotal-lever type, this
arrangement may be inverted such that the first switch member 41 is
of pivotal-lever type and the second switch member 42 is of
push-button type. Alternatively, both of the first and second
switch members 41 and 42 may be of the push-button type or the
pivotal-lever type. Further, both or one of the first and second
switch members 41 and 42 may be configured to slide linearly
relative to the switch case.
* * * * *